SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aa9b50f659de6fcc47865ef329c8133da8af29e048cf4a1b3991dd51133e76be' 
  AND token = 'dpdpuVSh7+rht5bcG9BVPwz5mVuKd0lQgD+vLuz+JwI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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