SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a8c91a31af9f0f007cd7c26ae1cba3666322f75962bb928b8374decb430f5d6' 
  AND token = 'drJV8gSWxwUsFrqGVXIxi4/CmgA0KXwIqpJ3dp/I+pY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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