SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b84e8dada9b06834b3203e5cbc03e061fc2e78923a44daf193557c03c1bc3177' 
  AND token = 'ftNOC0Z/H15QEBa85bP0j3U/XKaG79gKBxdbahFVATE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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