SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e820006fbba62e85b14a009da8c4ecd3dbd07ad2e687ee8f724b1e50eead49f0' 
  AND token = 'KnTzvMesdjrJh85XjBU6XSD1Ptrw9EoYDcv4ksAZ2II=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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