SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '50a546d80490fbdd25cc26984005a26db52fa99d44d6dc63313026000eda5a33' 
  AND token = 'fcKE/cC2lMt+vROfnlmB8Y3GbshoSftkIDoMjcxtvic=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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