SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '4867dd9cd484712831495a43519f99871bddc5a2fa2299449f333ef72bb65e2d' 
  AND token = 'SHpPbCiMRr01bx/iqxoPIMybmHVkG9kAMIheul7hF/E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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