SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9db3758dbb050414c58449c7147cfb15be80af73476be01dc278413feda4d739' 
  AND token = 'lrhDcLub0xge+LzchtvcRGtUhm7UyDbCEZZV4C82KWQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}