SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'dc0f870098439322ac5206a04901f6277e5bfe5bf89086db4378ec014a27b207' 
  AND token = 'xjZVjpQG+Tg/lAtzlu0oI0ofUzDPrhjCgfLmlYav/EI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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