SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a00c8eaa4ff94048be2b60c837898eef538948bccebe5d95fd61f6d2816970eb' 
  AND token = 'OFJDgqAwSoLcY1dV0+JBhtnYE6KQ34poDNYT0uQfdN0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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