SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '823d785436d80ace66813dd17ccbfaa86487a517a923c74587e18ad3b0390227' 
  AND token = 'qA3wdIBatLiozNU3Syo9zr7pV1/xoPyJ4Z2yVldLiSk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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