SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71d9d841dd1c14642539ec46e9237c2b05d872708c99d1034cce00b5f8582cf3' 
  AND token = 'T+dCU1/+ZKaw1U4qojKdzlx6JnTeqGQZNsjVLFRPck8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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