SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b515117b1d1ac6e4175e63717d25b39e993a82e3f82d9b0db7beea5da92b2139' 
  AND token = '3Km2G48PJFBsCGeIIeQjSehAUPYQaoR9KxNZRt34bjQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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