SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '803d5809f136ab4f5bfee7dc4120c7df8d77ff017564a8ab6ede063c84457b2a' 
  AND token = 'mEc+s+22pNtAFZj8tlyCEJqCAmnJrVYwGJubRJ2nQeg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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