SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fecfed650208bcac4da91719e671600c0a33d45032b8c2749d9f27208791dbef' 
  AND token = 'eqkmQIwXLQnPmflhlxYJvqWiSW/yUMTXQdTktTrpwxs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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