SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '773910f392746a732a82c0c9f0a7852442dca2f212d64c69b29930f9b9609adc' 
  AND token = 'vGdtrc34EDxDnR8bH04GeJZr3lv2gd9iJwQpCtmzvrc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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