SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f4a816675fc00f01401f4b67e49a80397714d5f429cf726baaf1cc55f553a1a' 
  AND token = 'BMbIkjp2iIYvPmapoDVTnv1h9fbGB7PKwuU/2gay4xo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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