SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d91793af602302efa46a3cb82d40e9446a6f6065de78a0ecc1632c1885c98e8' 
  AND token = 'kt7vDJhLwSWUimFjUTE6hyiRyBS8hSZyLWY2Krwogbc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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