SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f78efc730caa1099f26ec1161158993bcb76623fe6dcef2c4350ceab7e22bc35' 
  AND token = 'LHtWtVYk5QnTri9dCNUoAsrYRriaNjBfesRG+TWs+Bs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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