SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '84420c4350c204760443185ded0bdbfff02db053a19ce9da865dd7c45e92eef1' 
  AND token = '0Fs5l2tl51t30BJJZpCDAOUKr2CwJxrIDjFdVERSoDs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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