SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'b54134562d04c9927e4087547abc19104fc57de28a78253852a2754ea1927a62' 
  AND token = 'dVR2gmPBkGr0wb5x8p7xjYMPwa8n1iI7jh2reWaGm/E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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