SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3384b4a637cedbd0220319408cc4081fe7196a1e453a255e5b21da54bad6d44a' 
  AND token = 'aEgBAY5a1/o3aRWlJKm8ygTvoytHwK3hPdKfRCL5td0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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