SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4f4368e0c7de834f2d550601f0706eed3e945018fd2f53d767746f8bda102dc6' 
  AND token = 'NRTHCBqkaptQzUdN7bu2lNsyjkBIhm3yuoJRpEXetfg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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