SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7eaf2bb81102a8e2ede7e65575b09c6a7965a6780506df4ecd014e70d326e53b' 
  AND token = '1fU3lE3eBvqdNW9tDZmHemtZQJCuBInfm2f0bvFH4ZQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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