SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '451fee4d67d84efef1388d1e9f604284ccecfbe04f5650218b1e433ba735268a' 
  AND token = 'eKCVKEclt9/A36L3QWgEqbi/GWknKZHvKu1zFvjD7po=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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