SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e284397395bff42513a5fe8ca6db1a5dee4eeade9bfd47d92ad927761af3c11c' 
  AND token = 'nVIiCUAxn/xUYUdX0wn3NJFdGAeyrhwTO2rHl8KRX0I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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