SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d0378d012b2f0560bd202967fa7279d6d59068900f0731b282d7ac5d06eb8f3' 
  AND token = 'rITjSXz2fJRrL2bKtDQjdDhmYknqiaQwEMgPK5hOmSs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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