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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7cccbe51163eacf53aa1550cc206a6a1cdd2105a4ce2b9e41abfe36f9b2eb276' 
  AND token = '0/4HtqP0k5Wfwe31rSvLxsLb/uf8sJYogUtlfnzIhTo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}