SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e391caa7ce6df94edd55aace9c125f6472a30d4b262b78931338fc810ccba78' 
  AND token = 'Bw5aqb0z4+Jg9smuwCYDUhFUUORNRLNISQ/ert5AhB8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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