SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c83f55674b8ef7ae004fb3b89384a3fd348252d1231a8c868226dfebc5f0ff44' 
  AND token = '29XRRTXWESZHTS63Ggr242QCaAQ8+DeGiJLo0jddkJo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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