SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6c6fe2734638340765f1df7162c81e875e9c566df83ce2d49b39d1637785057' 
  AND token = '7023ht3+sbFMUyZCq/Ud9RPxm4bFgvlFvolcseIhyUo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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