SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '739abae4568982f7344cfff8a88513346a143730ad961bb3d751db9ee5e31c47' 
  AND token = 'hM+SHP8UzQAPfxAI1LhtYJLFcXxowCFhs2Vc+KNcqoI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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