SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b787e17d751425c6d04c0ff70963962f6062675ab4495a0d9da5426357f909cb' 
  AND token = 'l8X/s+rmVns8YK1JU8EULXcaij8OXomPjpc88tDwLPo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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