SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '6cdf9123e8bedb3670f8df4adebefc4ae677055da9c89460ee7a97621b7d391e' 
  AND token = 'xRe56hJEqNhOagu9vAhd68xzrVCGuMA389Rnlf7YTt0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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