SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3c4fabfecb7297f906f95d3cb0235e42e192eb91d03b15f51a2e298869b3c2a' 
  AND token = 'Ckad8WTwOXcGPKyClGZLnF8++poTTekv+vAGvPOgMtE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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