SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7cc5c135be55fa502387f017b34859000314c61bad8b659cc5d35e9b506de9b9' 
  AND token = 'cRYKIhpvGh+G7dQqfzPSDLjvjMsHO1GNfykVknf8MQM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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