SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a1c57763370b2975dcb70d96285a27f1a9de3845be2213a9169fd7885166d562' 
  AND token = 'qR5YUSruE03dnYYmIODtbjfBqekpTN/5R9rvuZ+x6Sk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}