SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '123b4ef3d0c482ff177a7919a121cabf77ee9e14435ee01ece7d02e186573de2' 
  AND token = '5oWA5Z5nBigAXSWlo+JyTgNas1yoJChKDYXvQikOhps=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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