SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '956a258e8c0700ee2d2a9394a49aeff7d2a576af8dc9170277050991c695bedf' 
  AND token = '2Oc89KIb1PdAphRCzRbzJeLOiQYOL+lCiW1p0eqsRHM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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