SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91ae263d2721938dafdefe4897d6094a470307a1d43a522d8f2be98059041fd6' 
  AND token = 'KxoDqRGouBxDk9vqla7BVhCz5DZ/Nl8pDzRJuHu+MAI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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