SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e6517612eb47870c425317f5defd5682227033f017bce6fb058c6b3891e70825' 
  AND token = 'KP9K2K+udGd8+UyuZatVItXUxKM4BdiCuVJba2U0eo4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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