SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7bbac20151dc8ac5e5011a26858362ed0d6a5816a21ffc9f4447441cdb74f042' 
  AND token = '56hoMb/XTg19Ep4sw2dr08MFvRHv7EBFmWNewednOAc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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