SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c219ce22ae5028d10670f5f4e5d6ba8f29bf9fe59d78ba9c3361d4658d9c0421' 
  AND token = 'gwBfbcz2db3USa4UoK5BE4eCyQzaBKZQ4BQaEkGLizo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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