SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0688717211e6e754f845ea8d2c3cf7e887d3138faae463187e21c605c213b589' 
  AND token = 'ECJyTGBijqD+XKopipMkjYEsKkGJkNLLwv8CZxFWHTQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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