SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76ee553f50dabb74abbed0dd6a79fc5fbf358830d08c53715228d1ff343bd82b' 
  AND token = 'NWEdS5u9ga/c4SsltLvLQcHZEapG7B5LYWy0weX87xk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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