SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f31d161297027fbe81209df6c3c98d1cb7042f760eacfef14646e999d1826c6' 
  AND token = 'comLg1ZU49Cdbm4rHCNKBSl/WItkz8cMY9gCwSLZRKY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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