SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '891476bed8c82464c5169a6f37152625c6fdd01b6087b1f590356fc173fd79a7' 
  AND token = 'nrMypaMsVdxBPIPznXtMGu4qLUggHVzmJ0N04haCKBc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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