SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e434f2883beec2390abf0ba104d5d2f652464758dba652b2c8c9d2673a615f08' 
  AND token = 'h/liBsqdLmaHvjEvPFn/UPqYKK6iq/2sOgCGselk8RI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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