SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '397392bfb852365f7a86e85d1bdcb7c79920e8dbd4c5d78206595267696dbcef' 
  AND token = '8e4sZ8gG6VkeLMjIsFmjJwiUHflM4bwBLVYbCq/nc+M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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