SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31761b39fc02261fe3cd8680bbcd708072922e2b2fd64f5e19e6e083eb5784c4' 
  AND token = 'pfQUfUUo7ObXFefn7JdOn5zVYhkH/K/zCrZ74ZR9ANM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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