SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b91fad1dd681ee1e453905914d7afd79bc6b856fa046a4351ce9bcf8ee1d674' 
  AND token = '7pZnW4CW1R1qobD0tQqbQ9m7YlaRUhfK6nGlO+y1Rlk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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