SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '36236167697c491c3db5077f1ad006b809a5c608802764ec684ab4029dc5bde4' 
  AND token = 'SVUcv3NfDqgUOwZYwmWPspyI2izvJkUuzTDhHMw+AQc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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