SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '109d898d9dde61918b6a24e36cf18ce134957b44649d546fd808a28c7f2f0836' 
  AND token = 'XvZzWj0oQGSuIwRrGtRtZfgVQYQZHZ58j6vRsWGDHAo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00074

JSON explain

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