SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '426b992fcdc21b29525102f08981d7c91ffde3a22c8b0f257425edc910637a5e' 
  AND token = 'xeTT+egNuprBlHiJAw01yVWR1zxSNGp+HOPIShg6ems=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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