SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a4a8a13c8248d51f349bb8137908a0a4085adbe70fe5e292eff12409a8aa962' 
  AND token = 'hxY0+wvDTOUajZCM486WV2BJYLas+EBPuNEhzvi5yIY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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