SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50274e9d279426f83e885e6f983c3895be102d30362675ec38057feb338d3483' 
  AND token = 'Rbr8PsHXObzvvEi24Mkvi8fstr9oRO77VAPKSaHNz2Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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