SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f5dc4d4623cfe7abe69935061e9ddb5bc5d05b002c5f9cc67f9b27635bfe1a15' 
  AND token = 'UjNq7VmJ92w5i65HmFCJ+Z2TkpmE2ZMij+mqFZ88YqM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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