SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '40e26f36e98d5968dc708cc95b084113cc74d115e5f8e084e65ca5b3d89f9103' 
  AND token = 'jtx5e9nXWjFVM3kSSNkurwYx1GnjDcJht5LrabMVPhg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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