SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f7f78119f2b5441238358bd225a714406c4e5146e80dd8cd566d86fca60e02ce' 
  AND token = '7nWJbmZjNEW2Jv88nYyXxhUa9YXakWdbaFvgOIYCPDs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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