SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3ecf0e716911a3a9f9bcd88f61c32e1f62485b0c12d0273456fc9ef5653faa3' 
  AND token = '/UxPvLjKVgB+z7mFzymtE/BTShbs5EcbQyy8qxWjhSY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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