SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'af981838f348f5156c51d3428eb187c78404f7902364c7caab0491172a933973' 
  AND token = 'J8Qy+KDmRPEy8AqOgWQcz2VYwDq37XwetxtZx5SwHbo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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