SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c75b4f38dd423c59d9562a33dc200885a2cb4b0e3a5ecdb8e3d09c4bd96beeba' 
  AND token = 'uxwBt5cgzVhBWboY3nnPxkplOYlYRiNknUWecLawo8M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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