SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cd1989119b351168a5ee9359f567118ce877700cd5944313423a7fc5d24337eb' 
  AND token = 'lFy86dotFLDuYYMtiUlAvCvM7ehWH8l+ysfDVVtQdhQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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