SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16870ed50816bb7600c86959745af7ed4a04d17756bda9cf09aa6b1e9437795b' 
  AND token = 'ubFMevFkz++FmrRMKEqaneA6s2GJeMQt3xzamdSJYHY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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