SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3dbbee9c7e5081bba226af806c6172cdfabcb623a1bca5bf593db2fc4afc8dd' 
  AND token = 'q81mnNJFffyi4m30oCqruoU9s+Qvun5uo5MdHIn8wkc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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