SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'ff92c623e5e4767454a1babaa97278c6351c2ac2f07dc4896e30a706c5f34498' 
  AND token = 'if2l8kJ2fzfEqaBpRE1HVw6FMLlTJmAWnV1kOAAbdOw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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