SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21a766b3d19f5582d8470df942f1106725e1f14a698318d06d81257726bc351c' 
  AND token = 'nPwmGi7McjGzvJdJ++hpGYcZ3xouqm7g3jwDQgzAJeo=' 
  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"
    }
  }
}