SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15e4ae75e10150fb6e1b50ef7f2d3f416f9254b0134ece0406b627e25920fd2f' 
  AND token = 'r5QgMl/1dkyk906dzx6rWuhmshOyeYXWYalmA1wDiQ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}