SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c11911e1bd35fc02d03bddcd22f7576093313382c25fd0b868d1f8ef936ea844' 
  AND token = 'xY8JOHsVXOfpdLHmaINMJ6Bk3QP06djnMCbOtQKFO2I=' 
  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"
    }
  }
}