SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df2d00af268e11c20f2ad0a36281cac56aeaf980567e5e1960f192564e56a17c' 
  AND token = 'JC18HyhvS1Rl1o/Hc/bNGe0U/UURjMMAvHJPJlms+ok=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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