SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0bd186dff55bd1a894e76f7c574a6fe9f0c4892f461db48e8c0b6a6c661f7e50' 
  AND token = '5z+PD3WJdAuoBdNhZZwBKOp+JrYmgCmDJUbWPapMB88=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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