SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4407db7a878965369acd156abc1fee7643b64641b2a35847c56e6bb116763962' 
  AND token = 'UdvpI5FxRK9SzjdSljOc+gFHCU4yYRpSMifr85VTwIo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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