SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c980a9349d15149ee4ca715c2ea17903517d6ad18e3b01a0a523676977ae7b95' 
  AND token = 'NzpjV6BQPLVcCKaYRymz+utvJ+h4C/BZHgD4iWSva/4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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