SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7b4ee2488b0126a62febea9c6ee246f321dab937949b110cd2eea6a106a79db' 
  AND token = 'nP7aHyTgyTYVV/GLwDQxyTHz9JBWZTV3JM43fCY39RM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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