SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7bbffeccb63aac11c6214be8b29e41917d8866cc807aa1486996e1d2b546ce79' 
  AND token = 'F7sSr1BqBpiP5t+ZLp4vMlbFYHYLRTfsfmp1VzpnJa8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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