SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8937bdba7c73a83f7459d2bfb59c32db10241884c16d0c82dabf14941cabdad' 
  AND token = 'z9Th0fllBWYnqwSMTZkfsPYLK3VpE+b4Qg2pIZR5JH0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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