SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12b051f923996782062105bccf013947354abfaa92b13c2815109f9421720348' 
  AND token = '14+9Je3Ut10GsXDVRwMTHhGTymUSakopdMXKpbetyhw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00009

JSON explain

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