SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75619c4df195bcad041cba1f065b0127c7e2cff2693163b5dcbec80e2f936269' 
  AND token = 'sVOvKf7dI0AXbDeOFZMA30AdfqIlWiek3UzRKCZIHvY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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