SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8489c3ae480ac0980937e675b564fabf323d0d1f8afd0f94fc2abebceffd9721' 
  AND token = 'El2MT+JDr14sBKBPdXy1PyyR9CZcQLxkTC6NWf3RRfU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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