SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c9fa391e34e7dfc2515c425768a6d4a914943c27f4129b5e40f98a7bbf724cb' 
  AND token = 'Fg+CXGqU75CuPlfYYkqn2y1aik2Ze3sDXBqrQUWaN4Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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