SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '787732d799c9643f32584135d7d6d693e4920269acc10e3cfa78f4ecf9e64d25' 
  AND token = '6YGxgFiatM/HaAFaSaV1bfWLaTjRVuQzxBEYqSRkgJc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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