SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '37c950ef5cf5bcd799a18f406f8ca32067e16124f1c35f11e39082fcf888b653' 
  AND token = 'v4+kYzVx1TJTVpSmgi69FhUykq2gBsZfxzduFRk/3Gw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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