SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '756df9b11543e72d1abb18b5f9346215a88d82f2ccd31de82eb09e65f25422f6' 
  AND token = 'qKUAPBAL5/L3I7qK9FSGfFBKcRgpzrS15Ftn03LoT0U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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