SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75ad3b7890154eb68545c4f143a630752f0d2ae91932dd6523a04d63d65fe508' 
  AND token = 'Sok8F42alDvASP3M+fZkL70kWfZ622/ylSsypPncHLQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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