SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec6c91b3071e491b004279b53677a9a6ab128221b96875b7f89a8cf276358b6b' 
  AND token = 'YuhIZfCovXuzG66r5wl2h/i3kC2QHIYD2diNGVkEHIg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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