SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a1eff3d40a250974a3248a139ca864420bb80a4f26dde87e287c4ad83bfd3543' 
  AND token = 'twX4owkf0yFLPEQPIB5n7rcGCOXqhApm19fdgrFDTis=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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