SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ff636b7f42bb9952ba6958abbb901c45f9af3991c9bcf7d3455753262c55ed4' 
  AND token = 'wPdpZN1hlPG/nciKWE9woR0UUv5ovRBmpCyeMIizTPg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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